1. Field of the Invention
The present invention relates to a magnetic head suspension for use in a rigid magnetic recording disk drive (hereinafter abbreviated to as HDD), and particularly to a wiring integrated suspension.
2. Discussion of the Background
A magnetic head suspension for HDD generally includes a flexure with a plate-shaped substrate that supports a magnetic head slider thereon, and a load beam that supports the said flexure in its lengthwise direction and includes a flexible portion that biases the slider flying on air by air pressures produced by rotation of a magnetic disk towards the disk surface.
There is a demand for supporting the magnetic head slider on the flexure, allowing the said slider to pitch and roll following the disk surface. To meet this demand, various flexures have been proposed. A most frequently used flexure among them is a so-called Watrous-type flexure, which is disclosed in the U.S. Pat. No. 4,167,765.
There is another demand in recent years for designing a magnetic head suspension having an arrangement that a part of wiring for connection between a magnetic head and an external signal member are integrally formed on the flexure to constitute a wiring structure, for the purpose of improving stability in attitude of a flying magnetic head slider, and reducing manufacturing steps of magnetic head sliders. This wiring structure generally includes a polyimide insulating layer laminated on the substrate of the flexure, a wiring conductor formed on the said polyimide insulating layer, and a polyimide protection layer covering the said wiring conductor.
FIGS. 15 and 16 illustrate a flexure 110 of the Watrous-type with an integrally formed wiring structure thereon, which is used for simultaneously achieving both demands as mentioned above. Specifically, FIG. 15 is a perspective view of a distal end portion of the said flexure 110, and FIG. 16 is a rear side view of the distal end portion of the flexure 110 as viewed from the opposite side to a side, on which the slider is supported. FIGS. 17 and 18 illustrate a suspension 100 with the flexure and a load beam 120 supporting the said flexure 110. Specifically, FIG. 17 is a side view of a distal end portion of the said suspension 100, and FIG. 18 is a view as viewed in the direction of the arrow E in FIG. 17. In FIG. 18, a reference numeral 150 represents a magnetic head slider.
As illustrated in FIGS. 15 to 18, the flexure 110 of the Watrous-type includes a plate-shaped substrate that, in turn, includes a base portion 111a and a gimbal portion 111b distally extending from the said base portion 111a. The said gimbal portion 111b includes a pair of lateral arm portions 113 distally extending from the lateral side edges of the base portion 111a in such a manner as to be located in the same plane as that of the base portion, a connection portion 114 for connection between a pair of the lateral arm portions 113 at the distal ends of said lateral arm portions, and a slider-mounting portion 115 proximally extending from the substantial center of the connection portion 114 and located in a space between the lateral arm portions. The connection portion 114 has an offset bending portion 114a formed thereon that allows the slider-mounting portion 115 to be located in a second plane closer to the magnetic disk than a first plane, in which the base portion 111a and the lateral arm portions 113 are located.
The wiring structure 130 integrally formed on the flexure 110 includes a first plane portion 130a formed on the base portion of the flexure and the lateral arm portions, a second plane portion 130b formed on the slider-mounting portion, and an inclined portion 130c located between the first plane portion 130a and the second plane portion 130b. The said inclined portion 130c is a wire-bridging portion, under which no substrate support exists. Omitting the wiring structure on the connection portion 114 prevents the wiring structure from being damaged during forming of the offset bending portion 114a of the said connection portion 114.
On the other hand, the load beam 120 is provided on the distal end thereof with a protuberance 121 that is adapted for abutting against the rear side of the slider-mounting portion 115. With this arrangement, the slider-mounting portion 115 can pitch around a first axis parallel to the lengthwise direction of the suspension and roll around a second axis orthogonal to the said first axis and parallel to a slider mounting surface, with the protuberance 121 being a fulcrum, thereby allowing the slider mounted on the slider-mounting portion 115 to pitch and roll following the disk surface. The slider-mounting portion 115 is offset to the lateral arm portions 113, so that the slider can be prevented from contacting the lateral arm portions 113, even if the said slider is of such a dimension as to straddle over the lateral arm portions 113.
Although the suspension of FIGS. 17 and 18 produces the aforementioned effects, it is accompanied by the following disadvantages. That is, the suspension of the arrangement illustrated in FIGS. 17 and 18 causes the inclined portion 130c to have stepped portion in order to be in conformity with the stepped configuration of the offset bending portion, This results in the formation of a bent part along the boundaries between the inclined portion and the first plane portion 30a or the second plane portion 130b, so that stress is concentrated into the bent part, thereby increasing the possibility of damaging the wiring structure.
FIGS. 19 and 20 illustrate a Watrous-type flexure 110xe2x80x2 of a different example with the integrally formed wiring structure, in which corresponding or identical parts to those of the flexure 110 have been given the same reference characters to omit a detailed description thereof. The flexure 110xe2x80x2 includes a pad stage 116 distally extending from the connection portion 114. The said pad stage 116 forms thereon the second plane portion 130b of the wiring structure. As is the case with the flexure 110, the entire region of the inclined portion 130c of the wiring structure is formed as the wire-bridging portion.
The flexure of FIGS. 19 and 20 includes the inclined portions 130c, the total length of which is longer than the connection portion 114, so that each of the said inclined portions has a gentle inclination as compared with the inclination in a corresponding offset bending portion 114a. Thus, the flexure 110xe2x80x2 of this arrangement lowers stress concentration in the inclined portions 130c of the wiring structure as compared with the flexure 110 as illustrated in FIGS. 15 to 18.
However, according to the flexure 110xe2x80x2 as illustrated in FIGS. 19 and 20, the entire region of each of the inclined portions 130c is formed as the wire-bridging portion with no support by the substrate, and the inclined portions 130c protrude sideways from the flexure substrate as viewed from above, so that any parts or matters are likely to contact the inclined portions of the wiring structure during assembly of the suspension or HDD, thereby increasing the possibility of damaging or deformation of the wiring structure. In addition, the wire-bridging portion which is not supported by the flexure substrate increases the possibility of causing the wiring structure to be vibrated by air pressures by rotation of the magnetic disk.
FIGS. 21 to 23 illustrate a flexure 110xe2x80x3 of still a different example, which figures respectively illustrate a perspective view of a distal end portion of the said flexure, a rear view of the said flexure, and a view as viewed in the direction of F in FIG. 22, illustrating the state that the load beam 120 is joined to the flexure. The said flexure 110xe2x80x3 includes a pair of reinforcing portions 117, which extend in the lateral direction of the flexure from the pad stage 116. The said flexure 110xe2x80x3 includes the inclined portions 130c each having a shorter length, thereby lowering the possibility of damaging or deforming of the wiring structure 130, and limiting the vibration. However, a problem arises in this flexure, as is the case with the flexure of FIGS. 15 to 18. Specifically, the inclination of the inclined portions 130c becomes sharper. This poses a problem of inviting stress concentration in the said portions.
An object of the invention is therefore to provide a wiring integrated magnetic head suspension that is capable of lowering stress concentration in a limited portion of the wiring structure to prevent damages or deformations of the said wiring structure, as well as limiting vibration of the wiring structure.
To achieve the above object, there is provided a magnetic head suspension including a wiring integrated flexure having a plate-shaped substrate for supporting a magnetic head and a wiring structure integrally formed on the said substrate for connection between the magnetic head and an external wiring member, a load beam joined to the said substrate in the lengthwise direction so as to constitute a suspension in conjunction with the said flexure. The said flexure substrate includes a base portion joined to the load beam, and a gimbal portion distally extending from the said base portion so as to support the magnetic head slider. The gimbal portion includes a pair of lateral arm portions each distally extending from a corresponding lateral side edge of the base portion, a connection portion for connection between a pair of the said lateral arm portions, a slider-mounting portion proximally extending from the connection portion and located in a space between the lateral arm portions, and a pad stage distally extending from the connection portion. The connection portion defines therein an offset bending portion that allows the slider-mounting portion and the pad stage to be located in a second plane closer to a magnetic disk than a first plane, in which the base portion and the lateral arm portions are located. The gimbal portion further includes a pair of reinforcing portions extending outwardly in the lateral direction of the flexure from the pad stage. The reinforcing portions each advance away from the second plane towards the first plane as they extend from the pad stage so as to have a curved cross section. The wiring structure includes a first plane portion located on the base portion of the flexure substrate and the lateral arm portions, a second plane portion located on the pad stage, and inclined portions as a transitional portion between the first plane portion and the second plane portion. At least a portion of each of the inclined portions of the wiring structure is formed on a corresponding reinforcing portion.
With the above arrangement, each inclined portion can have a smaller angle, so that the stress concentration in the inclined portions of the wiring structure can be lowered so as to effectively prevent damages or deformations of the inclined portions of the wiring structure. In addition, at least a portion of each of the inclined portions is formed on a corresponding reinforcing portion, thereby effectively suppress vibration of the inclined portions of the wiring structure, which vibration occurs with air pressures caused by the rotation of the magnetic disk.
The reinforcing portions each preferably have a width wider than that of the wiring structure which is formed on the said reinforcing portions, and at least a portion of each reinforcing portions defines a drawing-out portion to reduce rigidity of a corresponding reinforcing portion so as to be formed with a curved cross section during forming of the offset bending portion of the connection portion.
According to the above arrangement, the reinforcing portions each having a width wider than that of the wiring structure formed on the said reinforcing portions can prevent contact of the other parts or matters coming from sidewards of the flexure to the wiring structure, and more effectively prevent the vibration of the wiring structure. In addition, it is possible to omit an additional step of forming the reinforcing portions with the curved cross section by defining the drawing-out portion in the at least a portion of each reinforcing portions for reducing rigidity of a corresponding reinforcing portion, allowing the reinforcing portions to be formed with the curbed cross section during forming of the offset bending portion of the connection portion.
The reinforcing portions each may have a width narrower than the wiring structure formed on the said reinforcing portions in such a manner as to be formed with a curved cross section during forming of the offset bending portion of the connection portion, and may be formed so as to exist at least a portion corresponding to an outer edge of the wiring structure formed on the reinforcing portions.
According to the above arrangement, the reinforcing portions each having a width narrower than the wiring structure can be formed with the curved cross section during forming of the offset bending portion in the connection portion, achieving the omission of an additional step of forming the reinforcing portions with the curved cross section. In addition, the reinforcing portions each supporting at least an outer edge of a corresponding inclined portion can protect the wiring structure against the contact of any parts or matters accessing thereto from the lateral side of the wiring structure, and prevent the vibration of the wiring structure to some extent. As an additional advantage, the reinforcing portions each having a narrower width than the reinforcing portions in the aforementioned embodiments reduce undesirable influences over the attitude angle of the slider-mounting portion, or the rigidity of the gimbal portion against pitching motion and rolling motion.
The reinforcing portions are preferably connected between the distal ends of the lateral arm portions. This arrangement can effectively prevent the damages, deformations and vibrations of the wiring structure.
The lateral arm portions each preferably have a width wider than the wiring structure located on said lateral arm portions. This arrangement can also prevent the damages, deformations and vibrations of the wiring structure on the lateral arm portions.